Stock-Based Compensation - Restricted Stock Plan and Performance Shares (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 6 Months Ended |
Mar. 31, 2021 | Mar. 31, 2020 | Mar. 31, 2021 | Mar. 31, 2020 |
Restricted Stock | 2009 Restricted Stock Plan | | | | |
Restricted stock plan activity, number of shares | | | | |
Unvested and deferred at beginning of the period (in shares) | | | 141,680 | |
Granted (in shares) | | | 55,718 | |
Forfeited / Canceled (in shares) | | | (200) | |
Vested and deferred (in shares) | | | (23,629) | |
Unvested and deferred at end of the period (in shares) | 173,569 | | 173,569 | |
Expected to vest (in shares) | 173,569 | | 173,569 | |
Restricted stock plan activity, Weighted Average Fair Value at Grant Date | | | | |
Unvested and deferred at beginning of the period (in dollars per share) | | | $ 27.71 | |
Granted (in dollars per share) | | | 22.64 | |
Forfeited / Canceled (in dollars per share) | | | 35.49 | |
Vested and deferred (in dollars per share) | | | 32.80 | |
Unvested and deferred at end of the period (in dollars per share) | $ 25.38 | | 25.38 | |
Expected to vest (in dollars per share) | $ 25.38 | | $ 25.38 | |
Deferred Restricted Stock plan activity, number of shares | | | | |
Vested (in shares) | | | 23,629 | |
Deferred Restricted Stock plan activity, Weighted Average Fair Value at Grant Date | | | | |
Vested and deferred (in dollars per share) | | | $ 32.80 | |
Restricted stock plan activity, other disclosures | | | | |
Compensation expense | $ 524 | $ 340 | $ 1,019 | $ 556 |
Remaining unrecognized compensation expense | $ 2,496 | | $ 2,496 | |
Weighted average period for recognition | | | 1 year 2 months 4 days | |
Restricted Stock | 2009 Restricted Stock Plan | Employee | | | | |
Restricted stock plan activity, other disclosures | | | | |
Repurchase of stock from employees (in shares) | | | 10,439 | |
Average purchase price (in dollars per share) | $ 22.81 | | $ 22.81 | |
Restricted Stock | 2016 Restricted Stock Plan | | | | |
Restricted stock plan activity, other disclosures | | | | |
Compensation expense | | | $ 104 | 143 |
Deferred Restricted Stock | 2016 Restricted Stock Plan | | | | |
Restricted stock plan activity, number of shares | | | | |
Vested and deferred (in shares) | | | (21,435) | |
Restricted stock plan activity, Weighted Average Fair Value at Grant Date | | | | |
Vested and deferred (in dollars per share) | | | $ 31.97 | |
Deferred Restricted Stock plan activity, number of shares | | | | |
Outstanding at beginning of period (in shares) | | | 5,152 | |
Granted (in shares) | | | 7,398 | |
Vested and deferred (in shares) | | | (5,152) | |
Outstanding at end of period (in shares) | 7,398 | | 7,398 | |
Vested (in shares) | | | 21,435 | |
Deferred Restricted Stock plan activity, Weighted Average Fair Value at Grant Date | | | | |
Outstanding at beginning of period (in dollars per share) | | | $ 31.78 | |
Granted (in dollars per share) | | | 22.64 | |
Vested and deferred (in dollars per share) | | | 31.78 | |
Outstanding at end of period (in dollars per share) | $ 22.64 | | 22.64 | |
Vested and deferred (in dollars per share) | | | $ 31.97 | |
Restricted stock plan activity, other disclosures | | | | |
Compensation expense | $ 42 | 58 | | |
Remaining unrecognized compensation expense | 112 | | $ 112 | |
Weighted average period for recognition | | | 8 months 1 day | |
Performance Shares | | | | |
Restricted stock plan activity, number of shares | | | | |
Vested and deferred (in shares) | | | (13,200) | |
Deferred Restricted Stock plan activity, number of shares | | | | |
Vested (in shares) | | | 13,200 | |
Performance Shares | Certain Employees | | | | |
Stock-Based Compensation | | | | |
Remaining unrecognized compensation expense | $ 1,723 | | $ 1,723 | |
Restricted stock plan activity, number of shares | | | | |
Unvested and deferred at beginning of the period (in shares) | | | 61,362 | |
Granted (in shares) | | | 39,031 | |
Vested and deferred (in shares) | | | (13,200) | |
Unvested and deferred at end of the period (in shares) | 87,193 | | 87,193 | |
Restricted stock plan activity, Weighted Average Fair Value at Grant Date | | | | |
Unvested and deferred at beginning of the period (in dollars per share) | | | $ 43.22 | |
Granted (in dollars per share) | | | 28.23 | |
Vested and deferred (in dollars per share) | | | 38.43 | |
Unvested and deferred at end of the period (in dollars per share) | $ 37.24 | | $ 37.24 | |
Deferred Restricted Stock plan activity, number of shares | | | | |
Vested (in shares) | | | 13,200 | |
Deferred Restricted Stock plan activity, Weighted Average Fair Value at Grant Date | | | | |
Vested and deferred (in dollars per share) | | | $ 38.43 | |
Restricted stock plan activity, other disclosures | | | | |
Stock issued to certain employees | | | 11,366 | |
Compensation expense | $ 287 | $ 238 | $ 509 | $ 414 |
Weighted average period for recognition | | | 1 year 6 months 7 days | |